During recent years, an increasing number of swimming pools have been constructed in areas of the country where freezing temperatures are encountered during the winter. Due to the fact that water expands when it freezes, it is necessary to protect the pools, as well as the pipes and equipment servicing the pools, from damage caused by freezing. It has been found that in all but the most severe climates, the pool structure itself may be adequately protected by leaving the pool filled with water and placing logs or other floating devices in the water to prevent a solid layer of ice from forming on the surface of the water. Such protection, however, is not suitable for the pipes and equipment servicing the pool, since even in relatively temperate climates, the pipes freeze solid and, as a result of the expansion of the water, sometimes burst. To prevent the rupture of the pipes, it is therefore necessary to remove the water from the pipes prior to the time when freezing temperatures are encountered.
One popular method of accomplishing this is to lower the level of the water in the pool to an elevation just below the openings where the lines penetrate the pool wall. For convenience, these openings will be called outlets regardless of whether water flows into or out of the pool. The water is then blown from the lines and the lines are allowed to remain empty. In a variation of this, once the lines have been emptied, the outlets are plugged, and the water level in the pool is then returned to a near normal level. This latter approach is done to provide better protection to the pool structure itself. In either instance, thousands of gallons of water are lost through the process of partially draining and refilling the pool with water. In addition to requiring a considerable amount of time to partially drain and refill the pool, the cost of the water in many areas can be considerable.
Various devices have been conceived to eliminate the need for lowering the water level. Certain of these consist of a cofferdam like structure which may be affixed to the side of the pool to reduce the amount of water which must necessarily be removed to lower the water level to below the outlets. Examples of these devices are shown in U.S. Pat. Nos. 3,858,597 and 4,092,746. Other devices involve the use of relatively complex check valve systems, such as those illustrated in U.S. Pat. Nos. 4,281,422 and 4,368,550. Each of these types of devices has presented problems in use, including the complexity of the check valves and difficulties with affixing the cofferdam like structures to the side of the pool.
It has therefore among the objects of the invention to provide an inexpensive, simple device which will allow removal of water from the pipes and associated equipment servicing a swimming pool without draining the pool and without the difficulties associated with complex check valve systems and cofferdam systems. A further object of the invention is to provide a device which will facilitate keeping the pipes empty throughout the period when freezing conditions are anticipated.